This project is designed to determine how 2 designated control gene loci (I and B1) of the fowl effect their changes during melanogenesis with regard to the structural c and pk loci. During the year 1/1/77 - 12/31/77 we propose to: 1) validate heterokaryon complementation of c and pk melanocytes, 2) analyze B1 and I function in heterokaryons, and 3) screen for pigment production heterokaryons of wild type fibroblasts karyoplasts and mutant melanocytes or melanocyte cytoplasts to see if reprogramming of fibroblast nuclei can take place. BIBLIOGRAPHIC REFERENCES: Brumbaugh, J. and Lee, K. 1975. The gene action and function of two dopa oxidase positive melancyte mutants of the fowl. Genetics 80:333-347. Brumbaugh, J. and Schall, D. 1976. Restoration of pigment synthesis in mutant melanocytes after fusion with chick embryo erythrocytes. J. Cell. Biol. 70:222a.